When using variable capacity or uncapped partitions, analyzing CPU utilization becomes quite a challenge because the partitions can have a different effective capacity at each interval, depending on cycle availability in the shared pool and demand from the partitions.
Traditional ways to display CPU utilization or consumption consists of showing four percentages representing time spent in (1) user mode, (2) operating system mode, (3) I/O wait state, or (4) idle. However, displaying these four percentages does not provide enough information. For variably capacity partitions, these percentages are relative to a moving target (i.e., the effective capacity of the partition). Additional metrics need to be displayed, representing the real physical consumption in the interval, i.e. in real-time.